1. Field of the Invention
The present invention relates to an apparatus and a method thereof for forming a thin film, and more particularly, to an apparatus for forming a thin film on a substrate and a liquid crystal display device manufactured using the same.
2. Discussion of the Related Art
Due to rapid development in information technology, display devices have to display large amounts of information. Although cathode ray tube (CRT) devices have been commonly used as display devices, flat panel display devices that are thin, light weight, and low in power consumption have been actively developed. Among these, liquid crystal display (LCD) devices have been widely used in notebook computer monitors, personal computer monitors, office automation instruments such as photocopiers, and handheld devices such as cellular phones and pagers, because of their superior image resolution, color image display, and display image quality.
An LCD device includes an upper substrate, a lower substrate, and a liquid crystal material layer disposed between the upper and lower substrates. The LCD device uses optical anisotropy and birefringence characteristics of liquid crystal molecules in the liquid crystal material layer to produce image data by controlling an electric field applied to the liquid crystal material layers, thereby altering an arrangement of the liquid crystal molecules and varying light transmittance thereof.
An LCD device also includes a thin film transistor that functions as a switching element. Such an LCD device that includes the thin film transistor is commonly referred to as an active matrix liquid crystal display (AMLCD) device. An AMLCD device has high image resolution and can display moving images.
In general, an AMLCD device is manufactured through processes of cleaning substrates, forming patterns on the substrates, forming alignment layers, attaching the substrates, forming a liquid crystal layer between the substrates, and packaging circuits. The process of cleaning the substrates may be performed before and after the process of forming the patterns on the substrates, and particles on the substrates are removed by cleaning agents during the process of cleaning the substrates.
In addition, the process of forming patterns on the substrates is divided into a process of forming patterns on an upper substrate and a process of forming patterns on a lower substrate. During the process of forming patterns on the upper substrate, a color filter layer, a black matrix and a common electrode are formed on the upper substrate. During the process of forming patterns on the lower substrate, gate lines and data lines crossing each other to define pixel regions, a thin film transistor connected to each crossing of the gate and data lines, a pixel electrode connected to the thin film transistor in each pixel region are formed on the lower substrate.
Further, alignment layers are coated on respective substrates after patterns are formed thereon and are rubbed. Next, a sealant may be formed on the lower substrate to attach the lower and upper substrates. Liquid crystal then is injected between the attached substrates through an injection hole to form a liquid crystal layer, and the injection hole is sealed.
Moreover, the attached substrates including the liquid crystal layer therebetween passes through another cleaning process and a grinding process to form a liquid crystal panel. Integrated circuits are attached to the liquid crystal panel.
Apparatuses for manufacturing a liquid crystal display device include airtight chambers so that the processes are performed under high vacuum. A cluster chamber, which can treat a plurality of substrates in a short time, has been widely used. A cluster chamber includes process chambers, a load lock chamber, and a transfer chamber. In particular, in the process chambers, processes for directly treating substrates are performed. The transfer chamber stores the substrates and transfers the substrates into or out of the process chambers. The process chambers include a chamber for a plasma enhanced chemical vapor deposition (PECVD) apparatus and a chamber for a dry etch apparatus.
FIG. 1 is a cross-sectional view illustrating a dry etching apparatus for manufacturing a liquid crystal display device according to the related art, and FIG. 2 is a plan view illustrating an upper electrode of the dry etching apparatus shown in FIG. 1. As shown in FIG. 1, a dry etching apparatus includes a gas inlet 12 formed in an upper side of a chamber 10 and a gas outlet 11 formed in a lower side of the chamber 10. Gases are injected into the chamber 10 through the gas inlet 12 from a gas-storing unit (not shown) and exhausted from the chamber 10 through the gas outlet 11.
In addition, the chamber 10 includes a lower electrode 21 and an upper electrode 31 spaced apart from each other. A substrate 22, which includes a thin film to be patterned, is loaded on the lower electrode 21 inside the chamber 10. In particular, the lower electrode 21 is connected to an outer power supplier 13, which applies a radio frequency (RF) power to the lower electrode 21.
Further, the space between the lower electrode 21 and the upper electrode 31 often is referred to a reaction region. In particular, the upper electrode 31 is grounded and has a plurality of holes 32. As shown in FIG. 2, the holes 32 are arranged in a matrix manner across the upper electrode 31.
Referring back to FIG. 1, the chamber 10 further includes gas injection plates, 41, 42 and 43, disposed over the upper electrode 31 for evenly distributing the gases injected through the gas inlet 12. The number of gas injection plates, 41, 42 and 43, may vary based on demands. Thus, the gases are uniformly injected and provided to the upper electrode 31. Then, the gases are spread into the reaction region between the upper electrode 31 and the lower electrode 21 through the plurality of holes 32 of the upper electrode 31.
Moreover, the chamber 10 includes lower and upper shields 23 and 33 formed around the lower electrode 21 and the upper electrode 31, respectively. A part of the upper shield 33 extends into the reaction region, so that a density of plasma increases in an area corresponding to the substrate 22.
However, it becomes difficult for the dry etch apparatus of the related art to uniformly spread gases onto the entire surface of the substrate as the size of the substrate increases. In addition, the dry etch apparatus according to the relate art does not provide different etch rates for a center portion and an edge portion of the substrate even when a layer should be differently etched across the surface of the substrate. For example, an active layer is further etched in the edge portion of the substrate, while a passivation layer is further etched in the center portion of the substrate.